This invention relates to cable shield bonding devices which provide for making an electrical connection, usually a ground connection, to the electrically conducting shield of a cable.
A typical cable includes a bundle of insulated conductors enclosed within an electrical conducting shield which in turn is covered by an electrical insulating protective sheath.
At the end of a cable where the conductors are terminated at a terminal board or are spliced to the conductors of another cable or otherwise, continuity needs to be provided for the shield, as by connecting to the shield of another cable or to ground or otherwise as desired.
A variety of configurations have been provided for making connections to the shield of a cable. Two such devices are shown in U.S. Pat. Nos. 3,915,540 and 3,963,299. A crimp type cable shield bonding device is shown in the co-pending application of Mangrobang et al., Ser. No. 066,780, filed Aug. 14, 1979 and assigned to the same assignee as the present application. Another crimp type bonding device presently in use has a first relatively thick U-shaped clip with a second relatively thin U-shaped clip riveted therein. The inner clip has inwardly directed teeth at the outer edges thereof. The device is utilized by placing the cable sheath and shield within the clips and then compressing or crimping the outer clip together to clamp the cable sheath and shield therein.
The crimp type bonding device is less expensive and easier to use than the earlier bolted type devices. However there are certain disadvantages with the existing crimp type devices. The clamping force is achieved by the bending of the outer clip and in order to be assured of maintaining the clamping force, the outer clip must be made of relatively heavy material, hence increasing its cost. Also, the outer clip sometimes tends to relax its clamping force, thereby creating possiblities of poor ground connection. Also, since the outer protective sheath is formed of plastic or other electrical insulating material which tends to exhibit cold flow, an initially tight electrical connection formed during the crimping operation sometimes tends to loosen with the flow of the plastic resulting in a poor or inadequate ground.
It is an object of the present invention to provide a new and improved crimp type cable shield bonding device which is inexpensive and easy to manufacture and install. A further object is to provide such a bonding device which can be permanently attached in the clamping position. Another object is to provide a bonding device incorporating a spring member which will continue to exert a shield engaging force after crimping in place and after cold flow of the insulating sheath. An additional object is to provide such a bonding device with terminals for the outer clip and inner spring plate which are attached at a single point to the ground or other conductor.
Other objects, advantages, features and results will more fully appear in the course of the following description.